Answer:E
Explanation:
It is given that Energy of gamma ray is E=1.2 Mev
Shielding effect can be measured by measuring the fraction of gamma rays blocked by shield. If certain thickness will able to block half the radiation then to block 75% radiation we need to add same amount of thickness in order to block the remaining radiation.
i.e. 
fraction is blocked by 10 cm thickness
then remaining radiation is
another 10 cm thickness will block the remaining half radiation i.e. 
so total 75 % radiation will be blocked
The following choice that is NOT a way that machines provides a mechanical advantage is to change direction. The correct answer is A.
How dense the medium is in the compression part of the wave and how rare the medium is in the rarefaction part of the wave is a measure of the longitudinal wave's amplitude.
Answer:
Gravity
Explanation:
The source of the centripetal force that keeps the mass in a stable circle is gravity.
(b)equation is not balanced
